Corrugated sheet and method of manufacturing same

ABSTRACT

Disclosed is a metal sheet having a first major surface and an opposite second major surface, a first end and an opposite second end, and a first side edge and an opposite second side edge. The sheet has a plurality of parallel corrugations having a length defining a first axis extending along the sheet, a width defining a second axis extending across the sheet, and a depth defining a third axis extending through the sheet. The corrugations are formed by roll forming of the metal sheet. In transverse cross section, each of the corrugations comprises a substantially convex portion and a substantially concave portion. The substantially convex and concave portions each comprise a plurality of substantially linear portions with curved transition portions therebetween. The curved transition portions have a radius sufficiently small to cause plastic deformation of the metal sheet during roll forming of the corrugations. The substantially convex and concave portions each approximate a smooth curve.

CROSS-REFERENCE

This application claims priority to Australian Provisional Patent Application Number 2017902313, filed 16 Jun. 2017, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a corrugated sheet and a method of manufacturing such a sheet. The sheet has been developed primarily for use as an infill sheet in a fence panel. However, it will be appreciated that the sheet is not limited to this use and may also be used for other applications, such as wall cladding and roofing.

BACKGROUND

Some fences are constructed from panels comprising spaced upright support posts to which are attached sturdy upper and lower support rails. One or more infill sheet is fixed between the upper and lower support rails to provide privacy and/or to provide a barrier against the passage of people and animals through the fence. In many applications, the fence can be quite prominent and as such there is a continuing demand for fencing which is visually appealing. As such, the infill sheet(s), which comprise a large proportion of the fence panels, should ideally have aesthetic appeal whilst also being sufficiently strong to perform as a barrier and being cost effective to manufacture.

Some infill sheets that have previously been developed to address the above needs include roll formed corrugated metal sheets. Typically, such sheets include a plurality of parallel, smoothly curved crests and troughs extending between the side edges of the sheet and defining stiffening ribs and channels extending longitudinally between opposite ends of the sheet, the crests and troughs having a substantially sinusoidal wave form. Another example is the infill sheet disclosed in the present applicant's earlier Australian Patent No. 2009200462, the entire disclosure of which is incorporated herein by way of reference, which has a point of inflection between adjoining smoothly curved portions at the peak of each crest and the base of each trough to provide a distinctive and visually striking “breaking wave” profile to the sheet.

The present applicant has identified a problem with infill sheets that are roll formed with smoothly curving portions. This problem relates to the roll formed curves flattening out due to the inherent elasticity of the metal.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

Throughout this specification:

-   -   the words “comprise” and “include”, and variations such as         “comprises”, “comprising”, “includes” and “including”, will be         understood to imply the inclusion of a stated element, integer         or step, or group of elements, integers or steps, but not the         exclusion of any other element, integer or step, or group of         elements, integers or steps;     -   the terms “sheet of metal” and “metal sheet” will be understood         to mean a sheet substantially of metal, but which may also         comprise other materials, such as paint and/or galvanic         coatings; and     -   the term “base metal thickness” will be understood to mean the         thickness of the metal excluding any coatings, such as galvanic         or paint coatings.

SUMMARY

Disclosed herein is a sheet of metal, the sheet comprising:

a first major surface and a second major surface opposite the first major surface; and

a plurality of parallel corrugations having a length extending in a first direction along the sheet, a width extending in a second direction across the sheet, and a depth extending in a third direction through the sheet, the corrugations being formed by deformation of the sheet,

wherein, in a cross section through the sheet transverse to the length of the corrugations, at least some portions of the corrugations comprise a shape approximating a smooth curve, and

wherein the shape approximating a smooth curve comprises a plurality of first portions, wherein adjacent said first portions are oriented at an angle to one another and interconnected by second portions, the metal in the second portions being plastically deformed during forming of the corrugations.

Also disclosed herein is a method of corrugating a sheet of metal, the method comprising:

providing a non-corrugated sheet of metal having a first major surface and a second major surface opposite the first major surface;

deforming the sheet to form in the sheet a plurality of parallel corrugations having a length extending in a first direction along the sheet, a width extending in a second direction across the sheet, and a depth extending in a third direction through the sheet,

wherein, in a cross section through the sheet transverse to the length of the corrugations, at least some portions of the corrugations comprise a shape approximating a smooth curve, and

wherein the shape approximating a smooth curve comprises a plurality of first portions, wherein adjacent said first portions are oriented at an angle to one another and interconnected by second portions, the metal in the second portions being plastically deformed during forming of the corrugations.

Paragraphs [0010] to [0015] below disclose features that may be included in a sheet as defined in paragraph [0007] above and/or in a method as defined in paragraph [0008] above.

The metal in the first portions may not undergo plastic deformation during forming of the corrugations. The second portions may be curved and have a radius sufficiently small to cause plastic deformation of the metal when the sheet is deformed to that radius. The corrugations may be formed by roll forming the sheet. The first portions may be substantially linear.

The first and second major surfaces may be rectangular and bounded by:

-   -   a first end and a second end opposite the first end; and     -   a first side edge and a second side edge opposite the first side         edge.

Prior to being deformed, the sheet may have a thickness of between 0.2 mm and 0.6 mm or between around 0.25 mm and around 0.5 mm. The second portions may have a radius of between 1 mm and 10 mm or between 2 mm and 6 mm or of about 3 mm.

A curve of best fit of the shape approximating a smooth curve may have a radius of at least 5 times greater than the radius of the second portions or of at least 10 times greater than the radius of the second portions.

The peak of each crest and/or the base of each trough of the corrugations may be curved. A curve of best fit of the shape approximating a smooth curve may have a radius of at least 5 times greater than a radius of the curved peaks and/or trough bases or of at least 10 times greater than a radius of the curved peaks and/or trough bases or of at least 20 times greater than a radius of the curved peaks and/or trough bases.

A curve of best fit of the shape approximating a smooth curve may have a radius: of greater than 10 mm; or of between 10 mm and 200 mm; or of between 10 mm and 150 mm; or of between 10 mm and 100 mm; or of between 10 mm and 70 mm; or of between 10 mm and 60 mm; or of between 10 mm and 50 mm; or of between 20 mm and 200 mm; or of between 20 mm and 150 mm; or of between 20 mm and 100 mm; or of between 20 mm and 70 mm; or of between 20 mm and 60 mm; or of between 20 mm and 50 mm; or of about 40 mm.

The first portions may have a length: of less than 0.2 times the radius of the associated said shape approximating a smooth curve; or of between 0.05 and 0.15 times the radius of the associated said shape approximating a smooth curve; or of around 0.1 times the radius of the associated said shape approximating a smooth curve.

The corrugations may be defined by alternating substantially convex and substantially concave portions (in other words, portions of “reverse curvature”), and the at least some portions of the corrugations comprising a shape approximating a smooth curve may comprise the substantially convex and substantially concave portions. In some embodiments, a point of inflection between adjoining said substantially convex and substantially concave portions may be at a crest (and/or a trough) of the corrugations, for example to provide the corrugations with a “breaking wave” shape. In some embodiments, one point of inflection between adjoining said substantially convex and substantially concave portions may be at a crest of the corrugations and another may be at a location between crests and troughs of the corrugations in the third (i.e., depth) direction. In other embodiments, points of inflection between adjoining said substantially convex and substantially concave portions may be substantially midway between crests and troughs of the corrugations in the third (i.e., depth) direction, for example to provide the corrugations with a substantially sinusoidal shape. The radii of the curves of best fit of the substantially convex and substantially concave portions may be substantially equal.

The sheet may have a protective coating. For example, the sheet may be galvanised, such as with an alloy of zinc and aluminium, and/or may include one or more layers of paint. The protective coating may be applied prior to the sheet being deformed.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the principles disclosed herein will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is an isometric view of a corrugated sheet embodying principles disclosed herein;

FIG. 2 shows a cross section through the sheet of FIG. 1, the cross section being taken transverse to the length of the corrugations;

FIG. 3 is an enlarged view of part A of FIG. 2, showing one of the corrugations of the sheet; and

FIGS. 4 and 5 show transverse cross sections through alternative embodiments of corrugated sheets embodying the presently disclosed principles.

DESCRIPTION OF EMBODIMENTS

FIGS. 1-3 show a metal sheet 10 embodying the presently disclosed principles. The sheet 10 is substantially rectangular, having a first major surface 12, a second major surface 14 opposite the first major surface, a first end 16 and an opposite second end 18, and a first side edge 20 and an opposite second side edge 22. The sheet 10 has a plurality of parallel corrugations 24 having a length defining a first axis L extending along the sheet, a width defining a second axis W extending across the sheet, and a depth defining a third axis D extending through the sheet. The corrugations 24 are formed by deforming of the metal sheet, such as by roll forming.

A cross section through the sheet 10 transverse to the length of the corrugations 24 is shown in FIG. 2. The transverse cross section of sheet 10 is constant along axis L. As shown in FIGS. 2 and 3, each of the corrugations 24, in transverse cross section, comprises a substantially convex portion 26 and a substantially concave portion 28. The substantially convex and concave portions 26, 28 each comprise a plurality of substantially linear portions 26 a, 28 a with curved transition portions 26 b, 28 b therebetween. The curved transition portions 26 b, 28 b have a radius sufficiently small to cause plastic deformation of the metal of the sheet during roll forming of the corrugations 24. Despite being formed from a plurality of linear interconnected by curved transition portions, the substantially convex and concave portions 26, 28 each approximate a smooth curve.

The metal sheet 10 is roll formed from flat sheet steel having a base metal thickness of between 0.2 mm and 0.6 mm or between around 0.25 mm and around 0.5 mm, and the curved transition portions 26 b, 28 b may have a radius of between 1 mm and 10 mm or between 2 mm and 6 mm. Based on the yield strength and base metal thickness of the steel being roll formed, the radius of the curved transition portions 26 b, 28 b required to cause plastic deformation during roll forming of the curved transition portions can be determined. In the illustrated embodiment, the steel sheet 10 is roll formed from coil steel having a minimum yield strength of 550 MPa and a base metal thickness of approximately 0.35 mm, and the curved transition portions 26, 28 have a radius of approximately 2.8 mm.

In sheet 10, a curve of best fit for the substantially convex and concave portions 26, 28 has a radius of approximately 40 mm. As such, the radii of the curves of best fit for the convex and concave portions is more than 10 times greater than the radius of the curved transition portions. In other embodiments, the substantially convex portion 26 and substantially concave portion are differently configured such that the substantially convex portion 26 has a curve of best fit with a different diameter to that of the substantially concave portion 28.

In sheet 10, the linear portions 26 a, 28 a have a length of approximately 4.7 mm, which is around 0.1 times the radius of the curve of best fit for the substantially convex and concave portions 26, 28. In other embodiments, the ratio of the length of the linear portions 26, 28 to the radius of the curve of best fit for the associated substantially convex or concave portion 26, 28 may be greater than or less 0.1 and may, for example, be another value between around 0.05 and around 0.2 such that the substantially convex and concave portions 26, 28 may more closely or less closely approximate a smooth curve.

The corrugations 24 of sheet 10 are defined by an alternating (“reverse curvature”) pattern of substantially convex and concave portions 26, 28 across the sheet. The point of inflection between each adjoining substantially convex and substantially concave portion 26, 28 is at either a crest or a trough of the corrugations 24 to provide the corrugations with a “breaking wave” shape as best illustrated in FIGS. 2 and 3. A curved transition portion 30 is provided between each adjoining substantially convex and concave portion 26, 28 and defines the peak of each crest and the base of each trough of the corrugations 24. The curved transition portions 30 have a radius of approximately 1.4 mm.

The corrugations can repeat at a pitch in the range of about 50 mm to about 300 mm in a direction across the sheet 10 (i.e., parallel to axis W). In sheet 10, the corrugations repeat at a pitch of about 80 mm, with each of the concave and convex portions 26, 28 extending approximately 40 mm in a direction parallel to axis W. Thus, the base of each trough is substantially mid-way between two adjacent crest peaks. In other embodiments, each of the convex portions 26 may extend a greater distance in a direction across the sheet 10 than the concave portions 28, or vice versa, such that the base of each trough is offset from the mid-point between adjacent crest peaks.

The distance between the crest peaks and trough bases measured in a direction through the sheet 10 (i.e., parallel to axis D) can be from about 20 mm to about 200 mm, or more usually from about 20 mm to about 75 mm. In the illustrated embodiment, the distance between the crest peaks and the trough bases measured in a direction through the sheet 10 is approximately 26 mm.

Sheet 10 has a width of approximately 810 mm. Sheet 10 can be made in various lengths, such as lengths of approximately 1490 mm or 1790 mm. However, in other embodiments, sheet 10 can be wider or narrower and/or longer or shorter to suit a particular application.

Sheet 10 is formed from G550 coil steel complying with Australian Standard 1397_2011. The coil steel for sheet 10 has a galvanic coating overlaid by one or more paint layers.

To form sheet 10, the coil steel is cut to size and roll formed using a roll forming apparatus. Roll forming apparatus are well known in the art and generally have a plurality of pairs of forming rolls. The profile of sheet 10, including corrugations 26, 28, is formed as the coil steel passes through a nip of the respective pairs of rolls.

It will be appreciated that sheet 10 is ideally suited for use as an infill between rails and posts of a steel fence panel. However, it may also be used in other applications where a barrier is required and may, for example, be used as cladding for a wall or roof or as a shade element in an awning.

FIGS. 4 and 5 show transverse cross sections through alternative embodiments of sheets 10′ embodying the presently disclosed principles. Sheets 10′ have many features in common with sheet 10, with corresponding reference numerals indicating corresponding features with corresponding functionality. As with sheet 10, sheets 10′ also have corrugations 24 formed from substantially convex and concave portions 26, 28 made up of a plurality of substantially linear portions with curved transition portions therebetween. The points of inflection of the substantially convex and concave portions 26, 28 of sheets 10′ are, however, positioned differently to those of sheet 10 in order to create differently shaped corrugations 24; specifically, alternative “breaking wave” shaped corrugations and substantially sinusoidal corrugations. Persons of skill in the art will, however, understand that these are merely some examples of alternative corrugation shapes and that the presently disclosed principles can be applied to any of a myriad of other corrugation shapes having a portion that approximates a smooth curve.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Examples of possible variations and/or modifications include, but are not limited to:

-   -   the shape and/or size of the corrugations 24 may be varied from         those disclosed above and in the accompanying figures, for         example by having a greater or lesser height and/or a greater or         lesser pitch, such as may be provided by modifying the         substantially convex and concave portions 26, 28 to have a curve         of best fit with a larger or smaller radius, and/or by         increasing or reducing the radius of the curved transition         portions 30;     -   to more closely approximate a smooth curve, the ratio of the         length of the linear portions 26 a, 28 a to the radius of the         curve of best fit of the substantially convex and concave         portions 26, 28 may be reduced; and/or     -   the sheet 10, 10′ may be formed of a metal other than steel or         from a metal alloy. 

1. A method of corrugating a sheet of metal, the method comprising: providing a non-corrugated sheet of metal having a first major surface and a second major surface opposite the first major surface; deforming the sheet to form in the sheet a plurality of parallel corrugations having a length extending in a first direction along the sheet, a width extending in a second direction across the sheet, and a depth extending in a third direction through the sheet, wherein, in a cross section through the sheet transverse to the length of the corrugations, at least some portions of the corrugations comprise a shape approximating a smooth curve, and wherein the shape approximating a smooth curve comprises a plurality of first portions, wherein adjacent said first portions are oriented at an angle to one another and interconnected by second portions, the metal in the second portions being plastically deformed during forming of the corrugations.
 2. The method as claimed in claim 1, wherein the metal in the first portions does not undergo plastic deformation during forming of the corrugations.
 3. The method as claimed in claim 1, wherein the second portions are curved and have a radius sufficiently small to cause plastic deformation of the metal when the sheet is deformed to that radius.
 4. A method according to claim 1, wherein the first portions are substantially linear.
 5. The method as claimed in claim 1, wherein a curve of best fit of the shape approximating a smooth curve has a radius of at least 5 times greater than the radius of the second portions.
 6. The method as claimed in claim 1, wherein each of the second portions has a radius of between 1 mm and 6 mm, and wherein, prior to being deformed, the sheet has a thickness of between 0.2 mm and 0.6 mm.
 7. The method as claimed in claim 1, wherein a curve of best fit of the shape approximating a smooth curve has a radius of greater than 10 mm.
 8. The method as claimed in claim 7, wherein the radius of the curve of best fit of the shape approximating a smooth curve is between 10 mm and 100 mm.
 9. The method as claimed in claim 1, wherein each of the first portions has a length of less than 0.2 times the radius of the associated said shape approximating a smooth curve.
 10. The method as claimed in claim 9, wherein the length of each of the first portions is between 0.05 and 0.15 times the radius of the associated said shape approximating a smooth curve.
 11. The method as claimed in claim 1, wherein the corrugations are defined by alternating said substantially convex and substantially concave portions, and the at least some portions of the corrugations comprising a shape approximating a smooth curve comprise the substantially convex and substantially concave portions.
 12. The method as claimed in claim 11, wherein a point of inflection between adjoining said substantially convex and substantially concave portions is at a crest and/or a trough of the corrugations.
 13. The method as claimed in claim 11, wherein one point of inflection between adjoining said substantially convex and substantially concave portions is at a crest of the corrugations and another is at a location between crests and troughs of the corrugations in the third direction.
 14. The method as claimed in claim 11, wherein points of inflection between adjoining said substantially convex and substantially concave portions are substantially midway between crests and troughs of the corrugations in the third direction.
 15. The method as claimed in claim 11, wherein the radii of the curves of best fit of the substantially convex and substantially concave portions are substantially equal.
 16. A corrugated sheet of metal produced using a method of corrugating a sheet of metal, the method comprising: providing a non-corrugated sheet of metal having a first major surface and a second major surface opposite the first major surface; deforming the non-corrugated sheet to convert it into a corrugated sheet having a plurality of parallel corrugations, the corrugations having a length extending in a first direction along the corrugated sheet, a width extending in a second direction across the corrugated sheet, and a depth extending in a third direction through the corrugated sheet, wherein, in a cross section through the corrugated sheet transverse to the length of the corrugations, at least some portions of the corrugations comprise a shape approximating a smooth curve, and wherein the shape approximating a smooth curve comprises a plurality of first portions, wherein adjacent said first portions are oriented at an angle to one another and interconnected by second portions, the metal in the second portions being plastically deformed during forming of the corrugations. 